Project
summary 11/15/2002: Lake
Como is a 140-year old, 98-acre impoundment of Duncan Creek located in
the City of Bloomer, Chippewa County, Wisconsin.
It is a mostly urbanized, shallow and fertile body of water
situated in a large and agriculturally dominated watershed.
The lake is recognized as an important natural resource for the
community, and is considered a regional asset of environmental,
recreational and economic significance.
Lake Como is known and used primarily for fishing, peaceful
relaxation, wildlife and scenic enjoyment, and limited boating
opportunities. Recently,
the lake’s value has been limited by problems such as degrading water
quality, excessive sedimentation, nuisance aquatic weed and algae
growth, declining fishery habitat, and restricted boat accessibility,
among others. These
problems have prompted the community to take actions that will restore
the natural, economic and social values for the continued benefit of the
greatest number of public citizens. The
City of Bloomer desires to restore the lake bathymetry to approximate
it’s original contour. This
will entail the repositioning of soils on the lake bottom and the
removal of the excess foreign material that has accumulated over 140
years. Sediment traps will
be installed and maintained in the upper reaches of the lake where
feeder streams enter. The
Bloomer Community Lake Association has mapped the current and original
bottom contours of the lake to a precision of 1/10 foot vertical in a
grid of 50 foot or less intervals. Studies indicate approximately 250,000 cubic yards of foreign
material has been deposited over the original lake bottom. Alternate
‘A’ calls for the restoration to be done during the winter of 2003
– 2004 using mechanical methods while the lake has been drained to
facilitate the reconstruction of the Bloomer Mill Dam.
Bulldozers and excavators with high flotation tracks and mats
will be used to establish desired contours to the bottom.
Excess material will be transported by truck to a disposal site
less than 2.5 miles away. Alternate ‘B’ calls for the restoration to be done during the summer/fall of 2004 using a floating hydraulic cutter head dredge when the lake is at normal full pool elevation. The slurry would be pumped to the same disposal site described below. WPDES permits, monitoring and dewatering wells, settling and containment ponds will need to be designed, priced and included in this project alternate. The design for Alternate A is nearly complete. Alternate B is offered with the expectation it will include additional costs upfront for design, permitting, ground water monitoring, etc., but may provide lower material transport expenses. Bidders of Alternate B must include these costs and procedures to allow the City to evaluate total completed project costs using either method. The
disposal site is an industrial park vacant lot of approximately 13 acres
that is in need of up to 300,000 cubic yards of fill to be at grade with
surrounding lands. It is a
gently sloping area with sandy soils and a thin water table located
approximately 14 feet below the existing surface. A compacted soil berm with multiple erosion control measures
will contain and stabilize the spoils that are deposited, spread and
compacted upon the site. Since
the volume of water leaching into the surface or draining from the area
using Alternate ‘A’ is small and free from contaminates, it is
expected that a WPDES wastewater permit will not be required. The
proposed disposal site sits adjacent to land that was recently
considered as a site for a public school. The school district contracted to have soil borings and
testing done as part of their feasibility study.
All 15 boring samples, including two that are less than 50 feet
from the edge of the proposed disposal site, indicate sandy soils, an
absence of any hazardous materials and a thin water table 12.5 to 16.0
feet below the surface. The sediment has been sampled and analyzed. Boring sites were chosen with the consultation and assistance of WDNR and City personnel in an effort to select locations that would be most likely to contain hazardous substances. Testing as described by NR 149 indicated no defined hazardous materials were present in quantities that would require the material be treated as ‘hazardous waste’. It is mostly organic matter, averaging 45% solids that are finer than a #200 sieve. It is the desire of the Owner to remove as much of this material as feasible.
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